Looks to me that the image used for the mod is based off of the model from HL2. Same pose, same face, same clothes. Judging by the face, it looks like Group02 Male_01 to me. Here's a pic to compare: I.imgur.com

Yeah, that was what I was thinking too, just didn't have evidence to back it up.
If that is the case I'm not sure if this counts as stealing intellectual property, but it's going to be their problem in the end. We just give a heads up that it's noticeable.

Yes and no. I started with that model but then made its legs from scratch and changed his face by another model´s face, plus I made things like changing the clothes to what it was like in the 2001 trailer.